Just some Excel pointers. Volume of cylinder can be calculated as d^2*pi/4. Excel also has a function for pi, simply "pi()" and number can be squared with ^2 (or any other power) witch means the formula in e.g. cell D5. could be, "=E12^2*pi()/4*E13*1000" But as always great video.
Oh, I knew there were functions to simplify it in excel, I just had to search for them, as I don't know them of the top of my head. But I wanted to keep the formula as close as possible to a "human" language :) Thanks though. Good to know.
The compression volume above your piston is 1/6.5 the volume of your original stroke volume (based upon a 7.5:1). You know the original bore & piston size so doing the math ((2.94/2)^2 * Pi * 3.74)/6.5 gets you the compression volume of 3.91 cu in or 64.1 cc. without having to measure it. A .02 overbored piston will have a stroke volume of 25.7 cu in or 421 cc. So your resultant compression ratio is actually (421+64.1)/64.1 = 7.57:1 (even closer to 7.5:1!). All without getting your hand dirty or worrying about gasket volume or where the piston stop, etc.
Correct, but all that assuming that the 7.5:1 ratio in the spec is correct and no modifications to the head were done. The main reason to measure the actual chamber volume was to find out if it was "shaved" already and if there was room for more.
Wow! Excellent explanation and demonstration. Although I have done these calculations many times (the first time in 1963 for a Cadillac engine in an Allard J2) I watched the whole video because your explanation and calculations were so clearly presented. Thanks very much, Elin!
You know, you're smarter than I look. You are going places, kid. ;) I had to skip around, but I'm thinking that there may be a downloadable spreadsheet that can do this for a guy at home, specific to this engine? It's so much easier to send the head or complete engine off to the machinest, but this is totally doable if you push yourself to try and figure it out before having the machinest shave the head. Plus, they make mistakes also! I haven't had a problem, but my father in law did and it pushed back his project almost a year.
Many thanks for reminding me of how those calculations were done Elin. Great method of getting the combustion chamber cc.. I'm surprised at how low the CR was. Must have been reduced as part of the de-tune for emissions compliance.
Yes, Alexa is a great assistant :) she plays music for me and pauses when I tell her so I can film, I don't need to go back and forth. And of course she answers all my questions and does all my calculations since I use my phone to film and can't use it as a calculator.
Great video! I have never measured a combustion chamber volume, but wouldn't it be very precise to put the syringe on a scale before and after to measure the exact weight = volume of the water in the chamber?
If I’m not mistaken my 1969 TR6 was valued at 9.5 to 1. I presume that as years went on they detuned the engine to comply with environmental restrictions
Maybe they did for the US market, I know the TR6 produced around 150hp in the UK fuel injected version, no idea what it put out with carbs plus the reduced emission kit fitted and a lower compression head in the US but here's a link that explain a bit about it: www.tr-register.co.uk/forums/index.php?/topic/41903-us-vs-uk-spec/
I have a Honda k20 engine. I have 1mm oversized dished valves on the intake and I have stock size flat faced valves on exhaust side. Is this a good set up?
@@RustyBeauties At the 7:00 minute mark you explain that you are dividing the diameter by 2, then squaring the result and the multiplying by 3.14. I missed the part where you divide D to obtain R. My mistake. Can I get a silver star for paying attention? The one thing I remember that made me become interested in following you was when you explained the use of a timing wheel.
@@RustyBeauties Good point. When we had to rebuild my engine a few years ago we went with stock diameter sleeves in a couple of the holes so it wasn’t an issue.
I love the way you enjoy the teaching process!
Just some Excel pointers. Volume of cylinder can be calculated as d^2*pi/4. Excel also has a function for pi, simply "pi()" and number can be squared with ^2 (or any other power) witch means the formula in e.g. cell D5. could be, "=E12^2*pi()/4*E13*1000"
But as always great video.
Oh, I knew there were functions to simplify it in excel, I just had to search for them, as I don't know them of the top of my head. But I wanted to keep the formula as close as possible to a "human" language :) Thanks though. Good to know.
My Brain Hurts 😉
The compression volume above your piston is 1/6.5 the volume of your original stroke volume (based upon a 7.5:1). You know the original bore & piston size so doing the math ((2.94/2)^2 * Pi * 3.74)/6.5 gets you the compression volume of 3.91 cu in or 64.1 cc. without having to measure it. A .02 overbored piston will have a stroke volume of 25.7 cu in or 421 cc. So your resultant compression ratio is actually (421+64.1)/64.1 = 7.57:1 (even closer to 7.5:1!). All without getting your hand dirty or worrying about gasket volume or where the piston stop, etc.
Correct, but all that assuming that the 7.5:1 ratio in the spec is correct and no modifications to the head were done. The main reason to measure the actual chamber volume was to find out if it was "shaved" already and if there was room for more.
@@RustyBeauties Good Point. Enjoy your videos!
Wow! Excellent explanation and demonstration. Although I have done these calculations many times (the first time in 1963 for a Cadillac engine in an Allard J2) I watched the whole video because your explanation and calculations were so clearly presented. Thanks very much, Elin!
You know, you're smarter than I look. You are going places, kid. ;) I had to skip around, but I'm thinking that there may be a downloadable spreadsheet that can do this for a guy at home, specific to this engine? It's so much easier to send the head or complete engine off to the machinest, but this is totally doable if you push yourself to try and figure it out before having the machinest shave the head. Plus, they make mistakes also! I haven't had a problem, but my father in law did and it pushed back his project almost a year.
Merci Elin. Tu as le don de simplifier les choses compliquées.
Many thanks for reminding me of how those calculations were done Elin. Great method of getting the combustion chamber cc.. I'm surprised at how low the CR was. Must have been reduced as part of the de-tune for emissions compliance.
Nicely explained Elin, well done. Kind regards, Richard.
Thanks for the explanation.
Another great video Elin. Impressed with the excel work too👍 did ‘Alexa” or similar do your calculations? Very clever tool for the workshop.
Yes, Alexa is a great assistant :) she plays music for me and pauses when I tell her so I can film, I don't need to go back and forth. And of course she answers all my questions and does all my calculations since I use my phone to film and can't use it as a calculator.
Great video! I have never measured a combustion chamber volume, but wouldn't it be very precise to put the
syringe on a scale before and after to measure the exact weight = volume of the water in the chamber?
Of all the videos for Carlos to not give a thumbs down!
I need a drink.
We don’t need Carlos to have a drink! Cheers!
If I’m not mistaken my 1969 TR6 was valued at 9.5 to 1. I presume that as years went on they detuned the engine to comply with environmental restrictions
Maybe they did for the US market, I know the TR6 produced around 150hp in the UK fuel injected version, no idea what it put out with carbs plus the reduced emission kit fitted and a lower compression head in the US but here's a link that explain a bit about it: www.tr-register.co.uk/forums/index.php?/topic/41903-us-vs-uk-spec/
I knew David's brain would hurt :)
LOL
I have a Honda k20 engine. I have 1mm oversized dished valves on the intake and I have stock size flat faced valves on exhaust side. Is this a good set up?
Way lower compression ratio than I expected. Makes me wonder why I'm putting high octane gas in my Six ??
Yeah, it's been detuned for the US. Same engine with petrol injection in the UK has 9.5:1 compression.
So is there any advantage to using high test gas ?
Well that was very informative. Now Just post the excel file for us digit inept.
I did one for my BMW K100 Twin Cam headed 1098 Mini engine. Just so easy to flex using different head gasket thicknesses etc...
Sure, I will send it to you if you want. There are much better apps if you wanna use a ready to use tool
Pi x radius squared gives you the area of a circle. You used the diameter x 2.
Hmm… now you’re gonna make me watch the whole video again. I meant to use the diameter divided by two squared. Where was that part?
@@RustyBeauties At the 7:00 minute mark you explain that you are dividing the diameter by 2, then squaring the result and the multiplying by 3.14.
I missed the part where you divide D to obtain R.
My mistake. Can I get a silver star for paying attention? The one thing I remember that made me become interested in following you was when you explained the use of a timing wheel.
Isn’t it important to have gaskets for overbored cylinders to be at least as wide as the new bore? That may have a tiny change to your numbers.
Yes, it is, but these are not available for TR6. At least not to my knowledge.
@@RustyBeauties Good point. When we had to rebuild my engine a few years ago we went with stock diameter sleeves in a couple of the holes so it wasn’t an issue.
Good calculations! Did you have engineering training?
Nope, I graduated the university of life :)
Hi Elin there's an app for that!
I know. There’s also shops that would restore a car… I like to do things myself. Where is the fun if I use an app?
Stay in school kids!
Well that definitely is NOT the engine from the Java Green '75 TR6.... :-)
Who knows what rusty beauty showed up on the horizon…
I'm back in high school physics class and I DON"T LIKE IT!! (Oh yeah I failed!)